Novel CuO–SiO₂ nanocomposites: synthesis, kinetics, recyclability, high stability and photocatalytic efficiency for Rose Bengal dye removal

A novel CuO–SiO₂ nanoadsorbent, incorporating copper oxide (CuO) and silicon dioxide (SiO₂), has been successfully synthesized using three distinct preparation processes: Mode-A (solution and solution), Mode-B (solution and nanoparticles), and Mode-C (nanoparticles and nanoparticles). The investigation focuses on evaluating the efficiency of the CuO–SiO₂ nanoadsorbent, considering its synthesis process, reusability, and sustained performance over time, particularly in the removal of Rose Bengal dye. Characterization results revealed the formation of CuO–SiO₂ nanocomposites structure irregular shapes morphology across all three-preparation processes. The average particle sizes for Mode-A, Mode-B, and Mode-C nanocomposites were determined as 18.1 nm, 15.6 nm, and 14.8 nm, respectively. Furthermore, the band gap energies of the CuO–SiO₂ nanocomposites were measured at 2.2 eV, 1.8 eV, and 3.29 eV for Mode-A, Mode-B, and Mode-C, respectively. Remarkably, the CuO–SiO₂ nanocomposite prepared using Mode-B demonstrated superior photocatalytic activity in degrading the anionic dye Rose Bengal, achieving a degradation coefficient of 84.8%. In comparison, CuO NPs, tested under the same experimental conditions (120 min contact time, pH = 7, temperature of 25 °C, and solar light irradiation), achieved a degradation coefficient of 78.8%. These findings highlight the potential of the CuO–SiO₂ nanoadsorbent, particularly when synthesized via Mode-B, for effective and environmentally friendly dye degradation applications.